Indicating apparatus for electric circuits



(No Model.)

' E. THOMSON. INDICATING APPARATUS FOR ELECTRIC CIRCUITS.

No. 508,662. Patented Nov. 14, 1393.

l \/E TEI 3am AWN Q Cm Wu A \MTHESSEE- TLPATENT QFFIQE.

ELn-IU THoMSoN, OF SWAMPSCOTT, ASSIGNOR TO THE GENERAL ELECTRIC COMPANY, OF. BO TON, MASSACHUSETTS. 1

IN DlCATI N c APPARATUS- FoR ELECTRIC CIRCUITS.

1 SPECIFICATIONforming part of Letters Patent No. 508,662, dated November 14, 1893. I I Application filed 5111i .1893; Serial n. 479,330. (Nome-n1.)

To whom it ma/y conoern:

Be it known that I, ELIHUTHoMsoN, a citi zen of the United States, residing at Swampscott, 1n the county of Essex and Stateof M,as-

5 sachusetts, have invented acertain new and useful Improvement in Indicating Apparatus for Electric Circuits, of whichthefollowin g is a specification. v I

My invention relates to indicating appa- IO ratus for electric circuits, and has for its obect-to provide an instrument indicating the voltage of a distant part of theline when the load on theline and the drop are varied. It

1s well known that when a supply line or feed:

or line, extending to a distant; point, has no current traversing the samethe potential be tween the outgoing and return wires willbe practically the same'for the whole extent, of the line, and therefore that an indication of potential at or near the generating station will be true for the potential for the distant point; but when such a circuit carries a current to distant translating devices, its drop falsifies theindications of aninstrument anywhere near the generating station, and amodifled reading must be taken to deduce the true voltage, which would be definitely related to the voltage indicated unless there was a change in the drop due to some'change in the 0 circuit connections; but if the feeder line be permanent, this definite relation iscontinu: ally preserved. In such casesaninstrument constructed according to my invention may be applied to indicate the true voltage at the:

5 distant point. This result Iaccomplish by causing the volt-meter which indicates the potential to have a variable scaleunderjcontrol of the line current flowing throughjthe feeder, so that the indications of the volt-me 40 for needle will be changedby the movement of the scale in accordance with any change in the current traversing the circuit, and

, therefore in A correspondence with the drop which occurs on the circuit; Theinstrument 5 may be calibrated arbitrarily for the conditlons of use, and thereafter will remain ready foruse.

In the accompanying drawings Figure 1- is a frontel'evation; Fig. 2 a plan partly in sec 5 t f my imp oved e sn ing.i s rument-- Fig.3 is a detailed view. Fig.4 is adiagram of a system of distribution employing my invention, and Figs. 5, 6 and 7 are modifications.

In Fig.1, I is an index or indicator which moves in accordance with a variation of volt- 5 5 ageonaline. It maybe moved by electromagnetic action, as when a fine coil, indicated at V, Figs. l and 2, is pivoted between the poles of permanent magnet M, M,-and connected across the mains the differenceof potential of which is to'be indicated; suitable springs or other devices being used to return the index to zerowhen no voltage exists between the terminals of the coil which moves the index. The index might be moved by other means, as by the expansion ofa heated wire, like a (Jardew volt-meter, orit mightbe moved by electro-static attraction and reputsion, asin electro-static volt-meters. WVith its scale S fixed,such an instrument can only indicate the voltage at that part of the line to which its terminalsare connected; but in my invention I provide the scale S with means,

suchas a magnet D in a derived circuit, for swinging the scale into a position of greater and greater deflection as the current energizing the magnet D increases,a suitable retractor, or means for returning the scale to its original position being provided, as a spring Z pulling back the core ot'the direct 8o magnet D. It is desirable, though not essen tial, to have the scale swing from the'same center as the volt-meter index,or from centers inline therewith. The suspension of M thescale is shown as at s, Fig. 2, surrounding the pivots of the volt-meter coil'B, suitable supports being provided to maintain theparts in their proper relative positions; the details of the support are shown in Fig. 3, where the arm supporting the scale is marked S and its 96 swingbearing surrounding the center is in dicated at I). The power of the retractorspring Z and the turns of the magnet D, or its pulling power, are adjusted so that upon a certain current flowing it moves the scale so as to make the indicator, I, fallback partly toward zero and in a proportion depending on the drop on the line in which'the magnet D is connected, such line being the main line conveying current to a distant poin-t,'or a; too

feeder line in a system of electric distribuacting against a suitable spring or retractor tion. Thus in Fig. 4, G may represent a gen- Z" tends to carrythe index down-wards Win19 erator feeding the lines Z, Z between which, the other, K, acting in the same way agelllsli near the generator, is connected the volt-mea suitable retractor, tends to carry the index 70 ter instrument V, while the magnet D of Figs. downward likewise, but elevates the portion 1 and 2 is also markedD and servesto more pointing to the. scale by swinging the Index the scale and reduce the readings of the voltlaround. apivot- P. If the coil V is a volt-memeter in correspondence with the direct ourt'er coil,or is connected in a derived circuit rent traversing the line 6'. The line continacross the mains, while the coil D 1s in a line 75 1o nod for a distance at last reaches the lights g corresponding to D, Fig.l,,the zero woul be or other translating devices L, L, the number toward the upper part of the scale, and the of which may be varied. Now, assuming all index be brought down by the pull of e the lights out off fromsuch a system,and; the. ,core against theretractor Z, and i generator G delivering one hundred and ten for example, one hundred and ten volts. If 80 volts potentialnearits terminals, there will-be now a'current traverse the coil D, and the reone hundred and ten volts dilference of potentracting devices are suitably adjusted, the 1ntial at the distant part of the line, and thei-ndidex or pointer would he'carried sh'gh-tly back catororvolt-meter at V wi llpoin-t to1-1 0'onthe toward the zero in accordance with the cnrscale. It now lights are turned on by theeles- 3 rent flowing in Dand it will be readily seen 8 5 2o ingot switches, a current of increasing value, l that th-is modtfied-deviee might-housed to-aeas lights areturned on, passes through the complis-h thesame purpose-astheapparatusv mains l, l, to the distant points,andthe-vol=t- I of Figs-.- 1 and meter-may,byproperarrangementsatthegen' I-n- Fi-g. 6, the voltmeter cert V, act ng eratorG, continue to indicate one hundred and 1 against the retractor Z,draws down therndro 2 5 ten volts but owing to the lengtltand resi'ste catior l firointhe upper part ofi'the scale to mance ofitl1elines-Z,Z,and the current-traversing id icateone hundred and ten volts; when no them, there will be a drop involtage or loss icnrrenttra-verses the coil D; the-scale itselt ofi potential which will make the potentia hat may be made,fas S=,-elestic ,so-that when D the lights L, L, a certain amount below one i exertsa pull the- SGHilB= stretches. will be 95 3o hundred: and ten volts; and this-amount will manifest that any movexnentofi themdex, I, I

increase as the current in the line i-ncreases, marrying the. 1=l0- volt mark downwardandin' accordance withwell known: principles. 1 leaving the indicaten showing a-less poten Ifnow'the scale of the volt-meterbe moved in jti'alt would accomplish the same resntt as accordance with this increaseoficurrent and d'ces the apparatueofiEigs. l and 2i, Thedisr00 5 increase of drop so that the volt-meter nean tancebet-weeir the-divisions oi the seal'e may the generator reads lower inexact proportion: therefore beproportional l-y increased bythe to the-drop caused by the increased current, 5 movement of the scarle instead' of the: scale the generator G is adjusted to strengthen its being bodily moved, wh-iie thedivisi'ons re field so as to bring the index of thevol't-me i main the same,.as.sho-wn: inthe-priorfigiures- 5 40 ten again tone, which will lie-accompanied Referring again to Fig. 5, it is man-rfiest hya potential of one hundred and ten: volts that the actiens of' the eoilsvWD, might be atthe lamps-L,L,whiletherewill beahigher ,reversed, in that might have; the coarse voltage than one hundred and ten between; f ind ing amdbecome thedirect eurrentcoi l,

the=terminals of the volt-meter. The attendnd D housed 318 0116 volt-meter eoijl, if'the no however, in adjusting the voltage need iretractors z and Z" he proportioned to, g-i=ve only watch the volt-meter and keep it-oonlthein the requisite range-yinwhich case the stantlyat one hundred and ten,-while:the 'z'ero would be toward the: lower parrot the lamps are receiving their normal potential scale and the pn ll ofi the-coil Din response notwithstanding thehigher potential whieh to-voltagewouldi raise theindieator work-ing u 5 3o is beinggenerated. Instrumentsso cona-ron-nd thefulcrmn P,whi-le any current in structedmay beapplied to systems in which V would tendtobring?such-indicator toward a n-umberof feedersare-car-ried out and dethe zero. liver current intoan extended network, or in Still: anothermodification ofi my invention which a numberof generators,as= (it, G are isshowm in- Fig. I Iferethevolt-meter coil :20 coupled in multiple to feed a linear system; isindicated at-Va'nd pulls upon activate and they may be used wherever-itisdesired move a n i ndicator-I t'oward= the Iota-err betoindicate the conditions of voltageyat dis ing'conneoted acrossthe mains; 1 t, however, rant points dependent upon unvarying oonli's oarriedt together with the index I, on a ditions of line resistance, notwithstanding movable disk 'P,- pi voted= at its centerand :25 6o thervariations ofi load or current carried by bearingon its firont side-:ac-urved coreIUentheline. g'tering a stationary direct-current coil ID; a In Fig. 5 the com pensating action applied suitable retractor Z' being provided to pull tothe seale itselt or moving it bodily, asiin the core out of the stationary coil D- on the Figs 1 and 2, isreplaced by an action on the cessation or weakening ofi the current'. In 130 index itself. Bhus the index, I, may-hecarthisease current iin Dgwhenli ncreasing, gradried by two cores, as'at K, K, one ofwhioh uallypnlls in-the core K"and rotates-the disk T, and, in consequenceearrles the index I toward zero; according to the power of the retractor and the power ot' the coil D the range of motion given with acertain current is adjusted to be that amount which indicates the drop on the line due to the presenceof the load or current, while, as, before, an adjustment of the instrument to indicate one hundred and ten volts under load would mean not the presence of one hundred and ten volts: at the terminals of the coil V, but at the delivery end of the line. One hundred and ten volts have been simply takenlin illustration, and it will of course be understood that the normal potential requiredat the distant points may be higher or lower-than this and the adj ustment of the instrument made correspondingly. I

I-am aware that it has hithertobeen proposedto windan indicating instrument with two coils one of whichshall be a pressure coil or volt-meter coil moving an index, and the other of which shall .be a direct coil act-v ing difierentially with the pressure or voltmeter coil to reduce itsactionon. the magnetic part of the apparatus, and I do not herein claim such a device, the present inventionrelatingto independent means for compensation, whereby the voltmeter coil-.is 11nrestricted in its actionin moving its indicators, and wherebythe action ofthe direct current is also unrestricted in setting the scale or index. i

' The advantages accruing in the use of my. inventionare as follows: That it permits a variation of the retracting devices to be made independently; it. permits a change of the. Winding of either the pressure or direct current coils to be made, furthermore, my direct current adjusting devices may beelectro magnetic in character and may be used in combination with a pressure device whichis electro-static in character, or in combination with a device which dependsupon thermal actions for its indications. In fact, when ever I have described an electro-magnet in the direct circuit it may be by a proper con-, struction-replaced by otherdevices, such as thermic devices whose action is in response to an increase or decrease of current,'and Wherever-I have described a volt-meter device it can be any device which indicates the pressure or voltage by. electro-magnetic action, by .electro-static action, or by thermioor other action, and the two maybe combined in my invention whether they are dependent. on the same or different principles of work. ThusI am enabled to makean instrument dependent for its pressure indications on-thermic action, and which therefore is capable of being used on alternating currents as Wellas direct current, and as an instrument which is entirely independent of ,any relations of difference of lag or phase in such currents, which 65 would not be the case in an instrument detially as described.

pending upon differential electro-magneticaction, 7

As another example of my invention used with alternating currents of high'voltage, an electro-static volt indicator can be combined witha thermic adjustment dependent on the value of the main current and its heating effect, avoiding the difficulty introduced by insulation, and avoiding induction from electro-magnetic parts, which may increase the self-induction. 7

Having thus described my invention, what I claim, and wish to protect by Letters Patent of the United States, is

1. An electric measuring instrument, provided with an'indicator, devices adapted to move such indicator in accordance with variations of potential, a scale over which the indicator moves, and means responsive to the current in the load circuit and arranged'to vary the relative movement of the indicator and the scale in proportion to the drop on the load circuit,substantially asvdescribed.

An electric measuring instrument, comprising a volt-meter mechanism having a movable scale, and means actuated by the direct current adapted to move the scale.

3. In an. electric measuring instrument, an indicator, a coil responsive to variations of potential actuating the indicator, a scale over which the indicator moves, and a coil inthe direct or load circuit adapted to move the scale in accordance with the drop on the load circuit,vsubstantially as described.

4. In an electric measuring instrument, an indicator, a coil responsive to variations of potential and actuating the indicator, a suspended scale over which the indicator moves, and a coil in the direct or load circuit adapted to move the scale in accordance with the drop [0 5 on the load circuit, substantially as described.

' .5. In an electric measuring instrument, an indicator vibrating about a center, a coil responsive to variations of potential and actu-- ating the indicator, a scale over which the. no indicator moves suspended concentrically. therewith, and a coil in the direct or loadci-rcuit adapted to move the scale in accordance with the drop on the load circuit, substan- I I 5 6.- In an electric measuring instrument, an indicator, as I, actuatedby a coil, as V, adapted to respond to variations of potential, so as tomove over a movable scale, as S; in combination with a coil, as D, in the load circuitand adapted to move the scale S against the retractor-vspring Z inv accordance with the drop on the load-circuit, substantiallyas de-- scribed and set forth herein.

In witness whereof I have hereunto set my :2 5 hand this 29th day of June, 1893. l ELIHU, THOMSON Witnesses:

J OH-N-W. GIBBoNEY, BENJAMIN B. HULL. 

